Packaging machine for continuously producing sealed packages

ABSTRACT

There is described a packaging machine ( 1 ) for producing sealed packages ( 2 ) of a pourable food product from a strip ( 6 ) of heat-seal sheet packaging material. The packaging material ( 1 ) has a number of photocells ( 14 ), which are programmable externally as regards their setting parameters, are positioned facing the strip ( 6 ) of packaging material to detect optically detectable elements on the strip, and have setting means ( 26, 210, 300 ). The packaging machine ( 1 ) also has a control unit ( 16 ) connected to the photocells ( 14 ) and having enabling means ( 24 ) for enabling the setting means of a specific photocell ( 14 ), data downloading means ( 26, 240, 310 ) for downloading off the specific photocell ( 14 ) the setting parameters of the photocell, and data uploading means ( 26, 260, 330 ) for uploading onto the other photocells ( 14 ) setting parameters calculated as a function of the setting parameters downloaded off the specific photocell ( 14 ).

FIELD OF THE INVENTION

The present invention relates to a packaging machine for continuouslyproducing sealed packages of a pourable food product and featuringprogrammable photocells.

BACKGROUND OF THE INVENTION

Many pourable food products, such as fruit juice, UHT milk, wine, tomatosauce, etc., are sold in packages made of sterilized packaging material.

A typical example of such a package is the parallelepiped-shaped packagefor liquid or pourable food products known as Tetra Brik or Tetra BrikAseptic (registered trademarks), which is formed by folding and sealinglaminated strip packaging material.

The packaging material has a multilayer structure comprising a layer offibrous material, e.g. paper, covered on both sides with layers ofheat-seal plastic material, e.g. polyethylene.

In the case of aseptic packages for long-storage products, such as UHTmilk, the packaging material also comprises a layer of barrier materialdefined, for example, by an aluminium film, which is superimposed on alayer of heat-seal plastic material and is in turn covered with anotherlayer of heat-seal plastic material eventually defining the inner faceof the package contacting the food product.

As is known, such packages are made on fully automatic packagingmachines, on which a continuous tube is formed from the packagingmaterial supplied in strip form; and the strip of packaging material issterilized on the packaging machine, e.g. by applying a chemicalsterilizing agent, such as a hydrogen peroxide solution.

After sterilization, the sterilizing agent is removed, e.g. vaporized byheating, from the surfaces of the packaging material; and the strip ofpackaging material so sterilized is maintained in a closed sterileenvironment, and is folded and sealed longitudinally to form a tube.

The tube is filled with the sterilized or sterile-processed foodproduct, and is sealed and cut at equally spaced cross sections to formpillow packs, which are then folded mechanically to form the finished,e.g. substantially parallelepiped-shaped, packages.

Along the path of the strip of packaging material, packaging machines ofthe above type normally comprise a number of photocells facing, and fordetecting the passage of optically detectable elements on, the strip,e.g. optical register or reference codes, in particular bar codes,printed on the strip.

The photocells are connected to a control unit for controlling thepackaging machine, and which acquires the signals generated by thephotocells and, in known manner, accordingly enables the performance ofspecific operations on the strip of packaging material.

Photocells currently available on the market are also self-setting toadapt to specific operating conditions, by implementing a teach-inprocedure, which can be enabled either in local mode—i.e. by theoperator pressing a button on the photocell—or in centralized or remotemode—i.e. by means of an enable signal from the control unit to an inputon the photocell.

The teach-in procedure requires that a register code be fed past eachphotocell, which is done manually by the operator either feeding thestrip of packaging material past each photocell, or using a registercode impressed on a separate sheet of paper.

The teach-in procedure provides for automatically setting photocelloperating parameters such as: light spot color (red, green, blue) usedto detect passage of the register code on the strip of packagingmaterial and static intervention threshold.

Though extremely advantageous costwise, photocells of the above type,when used on packaging machines, pose several drawbacks preventing fulluse of the advantages available.

In particular, local mode enabling the teach-in procedure of eachindividual photocell takes a relatively long time, on account of boththe large number of photocells involved and the actual location of thephotocells, which, on packaging machines, are not always easilyaccessible by the operator.

Though faster than local mode, centralized enabling of the teach-inprocedure is also far from negligible by still involving a fairlyconsiderable amount of downtime.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a packaging machinefor continuously producing sealed packages of a pourable food productand featuring photocells designed to eliminate the aforementioneddrawbacks.

It is a further object of the present invention to provide a method ofsetting of photocells on a packaging machine for continuously producingsealed packages of a pourable food product, designed to eliminate theaforementioned drawbacks.

According to the present invention, there is provided a packagingmachine for producing sealed packages of a pourable food product, asclaimed in claim 1.

According to the present invention, there is also provided a method ofsetting of a photocell on a packaging machine for producing sealedpackages of a pourable food product, as claimed in claim 9.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred, non-limiting embodiment of the present invention will bedescribed by way of example with reference to the accompanying drawings,in which:

FIG. 1 shows a view in perspective, with parts removed for clarity, of apackaging machine for continuously producing aseptic sealed packages ofpourable food products from a tube of packaging material;

FIG. 2 shows a circuit diagram of a photocell in accordance with thepresent invention and forming part of the FIG. 1 packaging machine;

FIGS. 3 to 6 show flow charts of the operations performed to set theFIG. 1 packaging machine photocells.

DETAILED DESCRIPTION OF THE INVENTION

Number 1 in FIG. 1 indicates as a whole a packaging machine forcontinuously producing sealed packages 2 of a pourable food product,such as pasteurized or UHT milk, fruit juice, wine, etc., from a tube 4of packaging material.

The packaging material has a multilayer structure, and comprises a layerof fibrous material, normally paper, covered on both sides withrespective layers of heat-seal plastic material, e.g. polyethylene.

Tube 4 is formed, in known manner not described in detail, bylongitudinally folding and sealing a strip 6 of heat-seal sheetpackaging material; is filled with the sterilized or sterile-processedfood product by means of a fill conduit 8 extending inside tube 4 andhaving a flow regulating solenoid valve 10; and is fed by known devicesalong a vertical path A to a forming station 12, where it is cuttransversely and folded mechanically to form packages 2.

Packaging machine 1 also comprises a number of photocells 14, which arelocated along the path of strip 6 of packaging material, are positionedfacing strip 6, are held in position by respective supporting membersnot shown, and are connected to a control unit 16 for controllingpackaging machine 1.

More specifically, photocells 14 are arranged in pairs along strip 6 ofpackaging material to read pairs of side by side register codes on strip6. For the sake of simplicity, however, FIG. 1 shows only two photocells14 forming part of different pairs.

Photocell operating parameters can be set either in remote mode—i.e. bymeans of a signal from the control unit to an input on the photocell orby implementing a teach-in procedure, which can be enabled either inlocal mode—i.e. by the operator pressing a button on the photocell—or incentralized or remote mode—i.e. by means of an enable signal from thecontrol unit to said input on the photocell.

These procedures provide for automatically setting or self-settingphotocell operating parameters such as: light spot color (red, green,blue) used to detect passage of the register code on the strip ofpackaging material; static intervention threshold; dynamic interventionthreshold; static or dynamic photocell operating mode, whereby passageof the register code is detected respectively by comparing the photocellsignal level with the static intervention threshold, or comparingphotocell signal variations with the dynamic intervention threshold;signal deviation used to calculate the static and dynamic interventionthresholds, i.e. the variation in the photocell signal level betweendetection of the register code and detection of the background on whichthe code is impressed; and the enabled/disabled state of the teach-inprocedure enable button.

FIG. 2 shows the circuit diagram of one of photocells 14.

As shown in FIG. 2, photocell 14 comprises a casing 20 in which arehoused a known LED-type light emitting/receiving device 22 not describedin detail; a teach-in procedure enable button 24; a microprocessor 26connected to light emitting/receiving device 22 and enable button 24,and having a respective memory 28; and an input/output port 30 connectedto microprocessor 26 and control unit 16, and permitting two-way dataand signal exchange between microprocessor 26 and control unit 16 asdescribed in detail later on.

Memory 28 stores the photocell setting parameters mentioned, previously,i.e. the color of the light spot used to detect passage of the registercode; the static or dynamic intervention threshold; static or dynamicoperating mode; signal deviation; and enabled/disabled state of enablebutton 24.

Memory 28 can also store data relative to operation and the operatingstate of photocell 14—such as the total operating time of each LED oflight emitting/receiving device 22—to permit preventive LED maintenanceor prevent the use of rundown LED s.

Conveniently, input/output port 30 is a communication port preferably ofthe serial RS232 type implementing a 1200-baud, 8-bit, 1-stop, no-parityprotocol and 0-24 V signal dynamics.

Microprocessor 26 is designed to control operation of photocell 14 indifferent programmed operating modes, and in particular: in automaticsensitivity regulating mode; in local set mode, which can be enabled byeither enable button 24 or an enable signal supplied by control unit 16via input/output port 30; and in different centralized or remote setmodes, by which photocell is set directly by control unit 16 viainput/output port 30, as described in detail below with reference to theFIGS. 3-6 flow charts.

The FIG. 3 flow chart shows the operations relative to a first photocellset mode, which is implemented when the parameters of strip 6 ofpackaging material are known beforehand.

More specifically, in the first set mode, the operator—working from adata input device, e.g. a keyboard or a selector, packaging machine 1 isnormally equipped with—first enters into control unit 16 the feed speedand color of strip 6 of packaging material, and the color of theregister codes on strip 6, or one or more set of pre-set parameters(block 50).

On the basis of the strip parameters entered by the operator, controlunit 16 then calculates the setting parameters of photocells 14: in theexample shown, the dynamic intervention threshold and the light spotcolor (block 60).

At this point, control unit 16 uploads onto photocells 14—i.e. suppliesphotocells 14 with—the calculated setting parameters, which, viarespective input/output ports 30, are acquired by respectivemicroprocessors 26 and stored in respective memories 28 (block 70).

Finally, microprocessors 26 set respective photocells 14 to static ordynamic operating mode as a function of the uploaded setting parameters(block 80) A dynamic intervention threshold being uploaded ontophotocells 14 in the example shown, microprocessors 26 set photocells 14to dynamic operating mode.

When the first photocell set mode operations are completed, thephotocells commence detecting passage of the register codes using thesetting parameters.

FIG. 4 shows a flow chart of the operations relative to a secondphotocell set mode, which is implemented by control unit 16 when theparameters of strip 6 of packaging material are not known beforehand.

More specifically, in the second set mode, the control unit 16 firstacquires default photocell setting parameter values—in the exampleshown; default values of the dynamic intervention threshold and lightspot color—which may be stored in control unit 16 or entered by theoperator from the keyboard (block 100).

Control unit 16 then uploads the setting parameters onto photocells 14(block 110), and microprocessors 26 set respective photocells 14 tocorresponding operating modes (block 120).

At this point, control unit 16 feeds strip 6 of packaging materialforward, begins acquiring the signals from photocells 14 relative to thepassage of the register codes on strip 6 of packaging material, anddecodes the register codes (block 130).

Control unit 16 then determines, in known manner not described indetail, whether the register codes have been decoded properly (block140).

If the register codes have been decoded properly (YES output of block140), this marks the end of the second photocell set mode; conversely(NO output of block 140), control unit 16 determines further photocellsetting parameter values (block 150), and the sequence commences againfrom block 110.

FIG. 5 shows a flow chart of the operations relative to a thirdphotocell set mode, which is implemented by control unit 16 when theparameters of strip 6 of packaging material are not known beforehand.

More specifically, in the third set mode, control unit 16 first runsstrip 6 of packaging material to position a register code just before aspecific photocell 14 (block 200).

At this point, control unit 16 enables the teach-in procedure of thespecific photocell 14 by supplying the respective microprocessor 26 withan enable signal via input/output port 30 (block 210).

At the same time, control unit 16 runs strip 6 of packaging materialslowly and acquires the signal supplied by the specific photocell 14relative to passage of the register code (block 220).

Once passage of the register code is detected, control unit 16interrupts the teach-in procedure of the specific photocell 14 bysupplying a disable signal to respective microprocessor 26 viainput/output port 30 (block 230).

At this point, control unit 16 downloads off specific photocell 14 thephotocell setting parameters generated by the teach-in procedure—inparticular, the static intervention threshold, the signal deviation andthe light spot color—(block 240). Control unit 16 processes thedownloaded setting parameters, and in particular, calculates the dynamicintervention threshold and the light spot color (block 250), and thenuploads the calculated setting parameters onto all the photocells 14 ofthe packaging machine 1, including specific photocell 14 from whichsetting parameters were downloaded (block 260).

This marks the end of the third photocell set mode operations.

FIG. 6 shows a flow chart of the operations relative to a fourthphotocell set mode, which is implemented by control unit 16 when theparameters of strip 6 of packaging material are not known beforehand.

In the fourth set mode, the operator first enables the teach-inprocedure of a specific photocell 14 manually by pressing the respectiveenable button 24 (block 300).

This requires that a register code be fed past the photocell, which isdone by the operator either moving the strip of packaging materialmanually, or using a register code impressed on a separate sheet ofpaper.

Once the teach-in procedure is completed, control unit 16 downloads offspecific photocell 14 the photocell setting parameters generated by theteach-in procedure—in particular, the static intervention threshold, thesignal deviation and the light spot color (block 310). Control unit 16processes the downloaded setting parameters, and in particular,calculates the dynamic intervention threshold and the light spot color(block 320) and then uploads the calculated setting parameters onto allthe photocells 14 of the packaging machine 1, including the specificphotocell 14 from which setting parameters were downloaded (block 330).

This marks the end of the fourth photocell set mode.

The advantages of the present invention will be clear from the foregoingdescription.

In particular, equipping each photocell with an input/output portpermitting two-way data and signal exchange between control unit 16 andthe various photocells provides not only for centralized or remoteenabling of the teach-in procedure of each photocell 14, as with knownphotocells, but also for externally programming the setting parametersof photocells 14 by means of control unit 16 and so eliminating theaforementioned drawbacks of known photocells.

The present invention also provides for eliminating the drawbacks posedby known photocells as regards printing of the packaging material strip.

That is, known photocells require that the register codes be printed ona white background, which means, on the one hand, that one of the fourcolors typically used in printing the strip of packaging material isused solely for printing the background of the register code, and, onthe other, that white must necessarily be included in the printingprocess.

The present invention, on the other hand, provides for eliminating allthe above problems by permitting the reading of register codes impressedon any material or background, even on metalized materials, by simplysetting the appropriate light spot color and intervention thresholds ofthe photocells by means of control unit 16.

What is more, the above advantages are achieved with relatively minor,low-cost alterations to the photocells: costwise, a serial input/outputport is negligible with respect to the photocell, and can beincorporated in a traditional photocell with very little difficulty.

Clearly, changes may be made to the photocells as described andillustrated herein without, however, departing from the scope of thepresent invention defined in the accompanying claims.

1. A packaging machine for producing sealed packages of a pourable food product from a sheet packaging material; said packaging machine comprising: at least one photocell for detecting optically detectable elements on said packaging material, wherein said photocell is programmable externally as regards its photocell operating parameters; and control means connected to said photocell; wherein said photocell comprises input/output means permitting two-way exchange of photocell operating parameters of the photocell between said control means and said photocell.
 2. A packaging machine as claimed in claim 1, wherein said input/output means comprise a serial input/output port.
 3. A packaging machine as claimed in claim 1, wherein said control means comprise data downloading means for downloading off said photocell, photocell operating parameters of the photocell.
 4. A packaging machine as claimed in claim 3, wherein said control means also comprise data uploading means for uploading photocell operating parameters onto said photocell.
 5. A packaging machine as claimed in claim 1, wherein said photocell comprises setting means for setting photocell operating parameters; and wherein enabling means are provided to enable said setting means.
 6. A packaging machine as claimed in claim 1, comprising a number of said photocells; and wherein said control means comprise data downloading means for downloading off a specific one of said photocells its photocell operating parameters, and data uploading means for uploading onto at least one of the other photocells photocell operating parameters correlated to the photocell operating parameters downloaded off said specific photocell.
 7. A packaging machine as claimed in claim 6, wherein said data uploading means upload said photocell operating parameters onto all the photocells of the packaging machine.
 8. A packaging machine as claimed in claim 6, wherein at least said specific photocell comprises setting means for setting photocell operating parameters; and wherein enabling means are provided to enable said setting means.
 9. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include a static intervention threshold.
 10. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include a dynamic intervention threshold.
 11. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include a static photocell operating mode.
 12. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include a dynamic photocell operating mode.
 13. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include a light spot color.
 14. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include a signal deviation.
 15. A packaging machine as claimed in claim 1, wherein the photocell operating parameters include an enabled/disabled state of a teach-in procedure.
 16. A method of setting photocell operating parameters of a photocell on a packaging machine for producing sealed packages of a pourable food product from a sheet packaging material; comprising the step of programming the photocell operating parameters of said photocell externally; wherein said programming step comprises the step of providing said photocell with input/output means for permitting two-way exchange of photocell operating parameters of the photocell between said photocell and programming means.
 17. A setting method as claimed in claim 16, wherein said programming step comprises the step of downloading off said photocell the photocell operating parameters of the photocell.
 18. A setting method as claimed in claim 16, wherein said programming step comprises the step of uploading photocell operating parameters onto said photocell.
 19. A setting method as claimed in claim 16, wherein said programming step comprises the step of controlling said photocell to enable a setting procedure of the photocell.
 20. A setting method as claimed in claim 16, for a packaging machine comprising a number of said photocells; wherein said programming step comprises the steps of downloading off a specific one of said photocells the photocell operating parameters of the photocell, and uploading onto at least one of the other photocells photocell operating parameters correlated to the photocell operating parameters downloaded off said specific photocell.
 21. A setting method as claimed in claim 20, wherein said step of uploading onto at least one of the other photocells photocell operating parameters correlated to the photocell operating parameters downloaded off said specific photocell comprises the step of uploading said photocell operating parameters onto all the photocells of said packaging machine.
 22. A setting method as claimed in claim 20, wherein said programming step also comprises the step of controlling said specific photocell to enable a setting procedure of the photocell.
 23. The method of claim 16, wherein the photocell operating parameters include a static intervention threshold.
 24. The method of claim 16, wherein the photocell operating parameters include a dynamic intervention threshold.
 25. The method of claim 16, wherein the photocell operating parameters include a static photocell operating mode.
 26. The method of claim 16, wherein the photocell operating parameters include a dynamic photocell operating mode.
 27. The method of claim 16, wherein the photocell operating parameters include a light spot color.
 28. The method of claim 16, wherein the photocell operating parameters include a signal deviation.
 29. The method of claim 16, wherein the photocell operating parameters include an enabled/disabled state of a teach-in procedure. 